1. Field of the Invention
This invention relates to a disinfecting and cleaning system for contact lenses using a peroxo compound.
2. Statement of Related Art
The increasing number of wearers of soft or hard contact lenses necessitates the provision of a system of sterilizing and cleaning preparations which is both convenient and safe to use. Peroxo compounds which destroy germs and fungi are mainly used for this purpose, although any excesses thereof must be destroyed again before the lenses are replaced on the pupil.
Thus, CA U.S. Pat. No. 1,099,885 uses a redox system, for example of ascorbic acid and alkali percarbonate showing a strongly alkaline reaction in aqueous solution, for disinfecting and cleaning contact lenses, the contact lenses being placed in an aqueous solution of this redox system for about 5 minutes. After disinfection, the lenses are optionally rinsed with sodium chloride solution. They may then be replaced on the eyes.
According to published German application no. 33 29 922, contact lenses are disinfected and cleaned by placing them for 10 to 20 minutes in a solution of sodium chloride and a tablet (A) of urea peroxohydrate dissolved therein, then leaving them for 15 minutes in a fresh solution of sodium chloride and a tablet (B) for sodium ascorbate or a mixture of ascorbic acid and sodium carbonate dissolved therein and, finally, placing the lenses in a pure sodium chloride solution for at least 5 minutes. The lenses are then ready to be worn again.
U.S. Pat. No. 4,585,488 describes a process for disinfecting and cleaning contact lenses, in which the contact lenses are first placed for about 20 minutes in a hydrogen peroxide solution to which a catalase tablet is then added to decompose excesses of H.sub.2 O.sub.2. The enzyme acts within 5 minutes.
Hitherto, the most convenient system for the user has apparently been a disinfecting and cleaning system in which, for example, urea peroxohydrate in a sodium chloride solution is used together with a cationic, nonionic or, preferably, an amphoteric or anionic surfactant, and a catalyst for the subsequent destruction of the peroxide excess. A system such as this is described in U.S. Pat. No. 4,414,127. The separately packed components of the system, namely the urea peroxohydrate on the one hand and a solution of the surfactant, the catalyst and the sodium chloride on the other hand, are combined immediately before use. The user then has nothing further to do. The disadvantage here is that, although basically any surfactant may be used, it is said to be preferred to use two anionic or cationic surfactants selected from very special groups. In addition, a heavy metal salt, such as copper sulfate for example, is used as catalyst for the decomposition of excess urea peroxohydrate. However, the use of heavy metal salts is controversial and in many countries is legally regulated, e.g. on a regional basis in Germany (cf. the various wastewater laws of the individual Federal provinces). Nevertheless, treatment of the lenses still takes up to 4 hours.